UCA Idea

YJJPWrangler87

YJJPWrangler87

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Mar 12, 2006
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Raleigh
Alright, so I'm trying to decide on the design of an UCA bracket for an XJ, its a 3 link and after looking at the way RK has theirs, I was thinking of a way to do it for cheap and for it to be as strong or stronger. So I came up with these, please feel free to critique, approve, or completely trash the idea, I have my flame suit on:flipoff2: also for those not familiar to the RK design, the mount bolts to the DS of the XJ via 4 bolts.
Zack
 

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we just installed RK's 3 link on an xj and it looks like it will work pretty good. no testing yet so we will see. the only thing i would add to the RK set up is maybe some more gussets or bracing where the bolt goes thru the bracket. I guess thats what your drawing is showing here.
 
yeah..my buddy has a RK kit on his 90 XJ as well, and when i looked at the bracket, i wish it had more gussets, plus everythings gonna be made out of 3/8 yeah overkill, but if it fails on the road....bad things can happen.

Zack
 
You want that bolt to be horizontal so it doesn't max out when you droop...

I would also recommend using a wedge from some box tubing to brace the mount as opposed to plate triangles..

My $.02
 
the bolt should be horizontal...hmm i know what your saying but I can't see how that would work, must be me being up to late studyin for exams. heres a pic of how the RK style is set up. also what do you mean by a wedge with box tubing?

Zack
 

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i'm guessing he means cut a corner out of some box tubing and use it as a gusset rather than using the triangle plate gussets you have on your original drawing. and the bolt being horizontal so that the control arm can droop
 
yeah thats what i figured for the box tubing..heres a quick sketch....is this waht your talking about rich? I can see how there would be no binding...however, how strong would it be?
 

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I'm sure Rich means something like this. Use a piece of, say, 2x4 tube, but cut it into a triangle, if that makes sense...
 

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You could do the same thing with plate steel, cut the triangles and weld on the corners of the bracket and cut a rectangle and box the gussets in, same result...
 
yeah that does make sense rob, but is that what he means for the bolt to be horizontal...robs pic looks beefy as all get out but the one i drew...i wouldn't know how to brace that.

Zack
 
the bolt doesn't have to be horizontal...

Many of the extreme travel rock buggies mount the bolts verticle.

Just make sure the centerline of the bolt is perpindicular to the control arm at mid travel (same up travel and down travel). If not, you may not bottom the link out on up travel (less uptravel than down travel) but would on droop...

Make sense?

Find a good quality Uniball style joint (Johnny joint style) and you'll be fine. those things have plenty of room to flex, even with the bolt nearly verticle.

Rob
 
yeah...originally i had planned on doing a 4 link so i bought 4 RE large builder balls..when you mean mid travel does mid travel equal=ride height? If it does....regular ride height of the vehicle with stock everything? or is it something else?

Zack
 
With the bolt horizontal, you can brace that by boxing in the back side of the mount, and then running a support back from that to the frame. Take the pic in post #8 and adapt it to the new mount ;)

I will concede with Rob that the bolt doens't HAVE to be horizontal, BUT... that depends on how long that link is. If it's long, you may not bottom out the joint. If it's short, you might, and with only one upper link, the weight of the axle/wheels/tires will be pulling on that.. that would be bad.. mmmkay

Oh, and midtravel isn't necessarily ride height. it's *usually* a few inches drooped from ride height on something custom.
 
alright well the length of that UCA is 24 1/2" long...is that to long to run the bolt horizontal or does the bolt need to be vertical...and yeah rich i see how you would brace it now...I definately don't want this thing to break. That would be very bad

Zack
 
the horizontal bolt thing is gonna be a little difficult to do unless you weld a nut inside the boxed tube. i would think that if you cut one of the four faces of the boxed tube it would make it too weak. i think that making the bolt vertical is gonna be the easiest way to go and also is gonna be the easiest way to gusset and reinforce, but if you are gonna make the entire bracket out of 3/8 then you could do the horizontal design. i will draw you some brackets up on solidworks and you can look at them later.
 
Rich said:
the bolt doens't HAVE to be horizontal, BUT... that depends on how long that link is. If it's long, you may not bottom out the joint. If it's short, you might, and with only one upper link, the weight of the axle/wheels/tires will be pulling on that.. that would be bad.. mmmkay
Oh, and midtravel isn't necessarily ride height. it's *usually* a few inches drooped from ride height on something custom.
Click to expand...


Exactly. wether the joint bottoms out depends on the length of the link. The longer the link, the less movement you'll have on the joint. 24" or so, well, I don't really know if thats long enough or not. Mock the thing up with a link about the same length and see if the joint will bottom out.

What degree of misalignment do you have on your joints???

If you know the degree of misalignment (I think its 22*), then you can draw it up on the computer and know how much wheel travel you'll have with the given link length and the max degree of misalignment...

Post up your misalignment degree and I'll do it for you...

Rob
 
Oh yeah, mid travel usually isn't ride height.

If you have 14" of travel, then the point in the suspension geometry where you have 7" of up and down travel is the mid-point. At this point in your system, the link and the bolt in the control arm bracket should be at 90* (perpendicular to each other).

Rob
 
Assuming your links are not angled toward the center of the axle (I know they are but don't know how much), and assuming your links are exactly 24.5" center of bolt to center of bolt, you'll get approximately 9.3496" of suspension travel before the joint maxes out with the verticle bolt.

With the links angled in toward the center of axle, the distance from pivot to pivot decreases with increased angle. So, to be true, this measurement is not exact and will decrease the more you angle the links in toward the center of the axle.

Solution: run horizontal bolts, make longer links, or get different joints that allow more misalignment...


Rob
 
no thats just the length of the the actual tubing...from center to center...hmm i would add another 2 1/2's or so...so i could run the horizontal bolts and be fine...thats what im think i could do..i could beef it up really well and it should hold..plus give me more articulation..

Zack
 
i don't know the exact angle, like i said im modeling it after my buddys RK kit. I could always get that angle.

Zack
 
With the added couple of inches, you get movement up to 10.3037" of suspension travel.

Done properly, the horizontal bolt setup would work just fine.
 
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